gil1,
One of the things I try to get across to managers is not to worry about a single year's data. On smaller properties, specific factors can vary greatly from year to year (sex ratio, percent of yearling bucks that are spikes, antler growth per age-class, body weights per age-class, etc.). Look at the trends over several years instead of a single year's data.
I really wouldn't worry about some spike yearling bucks. Not only is that normal, in areas with later breeding most if not all yearlings are spikes.
Now if you have a November rut and year after year 70+% of yearlings are spikes, THEN I would consider nutrition to be a potential problem.